Method of manufacture of footwear



C. E. KAUFMAN METHOD OF MANUFACTURE OF FOOTWEAR Filed Jan. 14, 1966 Oct.21, 1969 United States Patent 3 473,178 METHOD OF MANUFACTURE OFFOOTWEAR Curt E. Kaufman, Waynesville, N.C., assignor to R0- Search,incorporated, Waynesville, N.C., a corporation of North Carolina FiledJan. 14, 1966, Ser. No. 521,247

Int. Cl. A43d 9/00 US. Cl. 12-142 6 Claims ABSTRACT OF THE DISCLOSUREThe invention refers to footwear such as shoes with an upper of leatherand a sole of porous elastomer.

It is customary to manufacture such footwear by first pulling the lowermargin of an upper of leather over a last to stretch and tighten theupper and securing the margin to a structural insole so thatsubsequently a prepared sole of porous elastomer can be cemented to theinsole and the margin of the upper.

According to the invention shoes with elastomer soles are improved by amore secure connection between upper and sole and by increasedflexibility as a result of the method of the invention, which arrangessteps of shoe manufacture, known per se, in a novel and moreadvantageous way.

The invention is clarified hereafter in connection with the drawingwhich shows in FIG. 1 a cross section of the device used for themanufacture according to the invention, at the completion of themanufacturing cycle before the finished shoe is removed from the device.FIG. 2 shows in a larger scale a cross section through the toe and FIG.3 a cross section through the heel of the shoe according to theinvention. FIG. 4 shows a view, partially in section, of still anotherexecution of the invention.

In the manufacture the upper 1 is prepared from pieces of leather. Atthe bottom margin 2 a welt 3 is fastened to the upper by the stitching4. While the material for the welt was heretofore selected to be atleast as strong as the material of the upper, i.e. stifi leather orsolid rubber, the invention provides that the welting material consistsof a highly compressible elastomeric material such as porous rubberpreferably of the kind having closed cells. It has been found that whilesuch material is strong enough to be stitched to the upper, it is at thesame time highly compressible which is an essential feature in theprocess steps explained hereafter.

The so-prepared pre-welted upper is placed on the last, loosely. Astructural insole is eliminated. The welt and with it the lower marginof the upper are held in their approximate position temporarily byclamps or threads, not shown. Then side frame 5, usually lengthwisedivided in two parts, is then placed adjacent to the bottom margin ofthe upper, but in a distance thereof. The clamps are then removed or thethreads cut so that the welt can slip back until its outer rim liesflush against the inside wall of the side frame. Push rods 6, adjustableby the threaded parts 7 and the nuts 8 are provided to hold the sideframe in a suitable distance from the upper so that a contact betweenthe side frame and the upper is com- "ice pletely eliminated. The bottomsurface 9 of the welt and the top surface 10 of the previously preparedsole 11 are covered with a heat-setting cement before the sole 11 isplaced into the corresponding cavity which is formed by the last 21, theside frame and a bottom plate 12. The bottom plate is provided with alinkage 13, 14, which carries the push rods 6 as well as the last 21.The closing lever 15 allows to hold the fore-mentioned parts together inthe desired position, or to swing the last with the side frame outwardlyfor the removal of the finished shoe. The bottom plate 12 and the lastare heated to a tempera ture sufficient for the heat setting of thecement on the surfaces 9, 10, a temperature which is sufliciently low soas not to damage the material of the upper, but usually sutficient tocause the material of the upper to shrink tightly to the last 21 andthereby receiving the set which assures satisfactory fit to the foot ofthe wearer. The compressibility of the welt material, such as porousrubber, is such that this spacing between upper and side frame can beachieved and after release from the side frame, the welt material canexpand and return to the shape and location in relation to the upperwhich is desirable in the finished shoe. After removal from the last 21,the edge of the welt and the sole is shaped and the appearance improvedby scoun'ng, i.e. abrading it on an abrasive belt. In FIG. 2 and FIG. 3the lines 16, 17 indicate the outside contour prior to the scouring tothe uniform line 18.

' As can be seen in FIG. 1 the compressibility of the welt 3 is usedtemporarily during the manufacture to eliminate any contact between themetal of the side frame and the leather of the upper. Thecompressibility also is important in that during the shrinking of theupper, the stitching 4 will at least at some parts of the perimeter moveoutwardly and compress the welt substantially. If the sole 11 alsoconsists of porous elastomer such as rubber, preferably identical to thematerial of the welt, it will compress sufficiently so that only a thinlayer of filler 19 might be required. Often the filler can be formed bya thin layer of a rubber mix with a blowing agent so as to form in situthe desired filling.

If desired, a more wear-resisting tread sole 20 can be cemented to thesole 11 simultaneously with the cementing of the sole 11 to the welt 3.

As can be seen in FIG. 3 the scouring of the outside rim of the porousrubber welt and the identical sole can be used to give the entire solealong its edge a shape different from the shape of the side frame 5. Ifa contour for the sole edge is desired which cannot be easily producedby scouring, or for any other reason, the invention provides that theporous rubber used for the welting and the sole is placed into thecementing device in a blown, i.e. expanded, but only incompletelyvulcanized or cured state. In such case the side frame 5 and/or thebottom plate 12 can then be used to impress upon the welt and sole thedesired final shape and configuration. In such cases the heating of theapparatus described above accomplishes not only the heat-setting of theupper and the heat-setting of the cement connecting welt and sole, butalso the final shaping of welt and sole as well as the molding andcuring of a sponge rubber filler. This can be seen in FIG. 4 where ascalloped or otherwise ornamented edge 22 forms the side of the sole.

What I claim is:

1. Method of manufacture of footwear with an elastomeric sole secured toa welt, comprising stitching a welt of highly compressible porouselastomer to the bottom margin of an upper, placing said upper and welton the last of a sole molding device, placing means across the bottom ofthe footwear to engage the footwear and tighten the upper on the last,placing a side frame of the molding device against the welt, removingsaid means from the footwear w' eiihif the welt to move outwardlyihtofight engagement with said side frame thereby 156mpressing the weltagainst saidjrarne, and thereafter securing an outsole to said welt. a Vv p 2. T he method as set forth in claim 1 wherein the outsole issecured to the Walt by adhesive. 3; The method as set forth in claim 1further charac terizedinthat a filler is cured between the last and theoutsole. 1 V 5 '4."The method as set forth in claim 1' further includirig the step of post-forming the welt to the configorar tioii of the sideframe. i I V I the steps of removing the footwear from the molding de '5The method as set forth in claim 1 further PATRICK :DILAWSON,'P-fi'fi1i1 y Examiner 9 .9 4 re u i the P rime e 9f 9919. b s uin 6. The method as set forth in claim 1 further characterized in thatthe sole is formed of porous elastorner.

